Gas barrier coatings of polyepoxide/polyamine products

ABSTRACT

Barrier materials for reducing the permeability of plastic packaging materials are provided, characterized as containing at least about seven percent by weight amine nitrogen, or a total of at least about 17 percent amine nitrogen plus hydroxyl groups. The barrier materials exhibit oxygen permeability of less than about 1.5 cc-mil/100 in 2  -day-atmosphere and a carbon dioxide permeability of less than about 15 cc-mil/100 in 2  -day-atmosphere at 23° C. and zero percent relative humidity. The barrier material can be formed from polyepoxide and polyamine. Optionally the polyamine may comprise prereacted polymeric resin formed from a polyepoxide and a polyamine. Multilayer packaging materials and multilayer containers including the polyamine-polyepoxide barrier material are part of the invention.

RELATED APPLICATIONS

This application is a divisional of application Ser. No. 07/767,458,filed Sep. 30, 1991, now U.S. Pat. No. 5,300,541, which was acontinuation in part of U.S. patent application Ser. No. 07/656,662filed Feb. 19, 1991, now abandoned, which is a divisional of U.S.application Ser. No. 07/367,992, filed Jun. 19, 1989, now U.S. Pat. No.5,008,137, which was a continuation of U.S. Pat. No. 07/152,176, filedFeb. 4, 1988, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to barrier materials, curable coatingcompositions for forming such materials, and to packaging materialsand/or containers including barrier materials. The barrierssubstantially reduce the permeability of gases such as carbon dioxideand/or oxygen through packaging materials.

Plastics have found increasing use as replacements for glass and metalcontainers in packaging, especially of foods and beverages. Theadvantages of such plastic packaging includes lighter weight, decreasedbreakage (versus glass) and potentially lower costs. However,shortcomings in the gas-barrier properties of common packaging plastics,such as polyolefins, e.g., polyethylene and polypropylene, poly(ethyleneterephthalate) and polycarbonates, present major disadvantages in thepackaging of many foods and beverages. For example, many foods andbeverages are sensitive to oxidation and must be protected from oxygento prevent discoloration or other detrimental effects. Further, plasticbeverage containers suffer comparative shelf-life problems versus glassor metal due to the loss of carbon dioxide through the plasticcontainer.

Numerous barrier coatings have been developed including, e.g., barriermaterials based on thermoplastic, crystalline resins such as vinylidenechloride or ethylene-vinyl alcohol. Each of these materials havedrawbacks. Ethylene-vinyl alcohol-based polymers lose barrier propertiesupon exposure to water, and packages of this material cannot generallyundergo retort, i.e., heating under pressurized steam for pasteurizationwithout loss of barrier performance. Vinylidene chloride-based polymershave been recognized as having excellent gas-barrier properties, butpreparation of such vinylidene chloride-based polymers must generally bedone under high pressure. Further, since vinylidene chloride-basedbarrier materials include halogen atoms, the disposal of such materialsvia incineration poses environmental problems. In addition, bothvinylidene chloride-based polymers and ethylene-vinyl alcohol basedpolymers exhibit loss of adhesion after undergoing retort.

U.S. Pat. No. 2,830,721 (Pinsky et al.) discloses apolyamine-polyepoxide barrier coating for plastic containers. Thepurpose is to reduce the permeation of organic solvents throughpolyethylene containers. For polymeric food and beverage containers, itwould be desirable to provide barrier coatings that have lower oxygenand/or carbon dioxide permeabilities than those disclosed in the Pinskyet al. patent.

SUMMARY OF THE INVENTION

The present invention concerns barrier coatings having exceptionally lowoxygen and/or carbon dioxide permeabilities which are suitable for useon polymeric containers and other packaging materials. Such barriercoatings are based on a polymeric reaction product of polyamine andpolyepoxide. It has been discovered that the permeability of this typeof barrier coating can be significantly reduced by enhancing the aminenitrogen content of the polyamine-polyepoxide reaction product. Thebarrier coating polymers of the present invention are characterized ascontaining at least about seven percent by weight amine nitrogen basedon total weight of the polymer. Exceptionally good barrier propertieswere found to be attained at amine nitrogen contents of at least tenpercent. (Weight percents herein are expressed on the basis of solidresin content.) The expression "amine nitrogen" is intended to excludeother nitrogen containing groups such as amides and urethanes.

In addition to the amine nitrogen content of the polyamine-polyepoxidereaction product, a secondary factor in reducing permeability of thecoatings of the present invention is the hydroxyl group content of thepolyamine-polyepoxide reaction product. Hydroxyl group content of atleast 6 percent by weight of the reaction product has been found to bebeneficial. Even better barrier properties have been attained withhydroxyl group contents of at least 10 percent. At the higher hydroxylgroup contents, it has been found possible to obtain good barrierproperties with smaller amounts of amine nitrogen in the reactionproduct, provided that the total of the hydroxyl group content and theamine nitrogen content is at least 17 percent. In this embodiment of theinvention, the polymeric gas barrier material has a preferred aminenitrogen content of at least 6 percent by weight based on the totalweight of the polymeric gas barrier material.

When cured, the coatings of the present invention have been found toexhibit oxygen permeability of less than about 1.5 cc-mil/100 in²-day-atmosphere. In preferred embodiments, oxygen permeability of lessthan about 1.0 and most preferably less than about 0.5 cc-mil/100 in²-day-atmosphere can be achieved. Low carbon dioxide permeability may beattained by the barrier coatings of the present invention instead of orin addition to the low oxygen permeability, although both propertiestend to decrease with increasing amine nitrogen and/or hydroxyl contentof the coating polymer. Carbon dioxide permeability of less than about15 cc-mil/100 in² -day-atmosphere (measured at 23° C. and zero percentrelative humidity) has been attained by barrier coatings of the presentinvention. Preferred embodiments exhibit carbon dioxide permeability ofless than about 3 and most preferably less than about 1.0 cc-mil/100 in²-day-atmosphere.

The polyamine-polyepoxide polymers that comprise the chief film-formingresin of the barrier coatings of the present invention are cured in situfrom two components that are mixed immediately prior to application ontoa plastic substrate. In one embodiment of the invention, the polyaminecomprises one component and the polyepoxide comprises the othercomponent. In another embodiment, one of the components may comprise aprereacted adduct of the polyamine with some of the polyepoxide, and theother component comprises polyepoxide to complete the reaction. Bothembodiments have distinct advantages.

In the embodiment involving prereacted adduct, the adduct is provided bythe reaction of a polyamine having up to about two primary aminonitrogen groups per molecule and a polyepoxide. Thereafter, the adductis reacted with additional polyepoxide to form the barrier coating.Forming the adduct by a preliminary reaction has the advantage ofincreasing molecular weight while maintaining linearity of the resinproduct, thereby avoiding gellation. Using a polyamine having no morethan two primary amino groups to make the adduct serves to avoidgellation in this embodiment. Additionally, the usual time periodrequired for ingestion of epoxy and amine reactants before applicationonto a substrate is reduced or eliminated by the prereaction of theadduct.

Not all of the embodiments of the invention require the step ofprereacting an adduct. It has now been found that excellent barriercoatings having at least seven percent amine nitrogen can be producedwithout the step of prereacting polyamine and polyepoxide to form anadduct. Instead, substantially all of the polyepoxide required for thecoating may be blended with the polyamine, and after allowing for aningestion period, may be applied to the substrate and cured in place.Not only is a prereaction step eliminated, but advantages have beenfound for directly blending polyamine and polyepoxide to polymerize to acoating. This embodiment permits the use of higher resin solids contentin the coating composition (preferably greater than 50 percent) andcorrespondingly lower volatile organic solvent content. Not only is thelower organic solvent content desirable from an environmentalstandpoint, but higher solids content is advantageous for providingadequate coating thickness on high speed coating lines.

Additional advantages result from the non-prereacted embodiments of thepresent invention. Higher solids content is accompanied by lowermolecular weight, which yields advantages in the type of solvents thatcan be used in the coating compositions. The flow properties of acomposition comprising a relatively low molecular weight resin areinherently better, thereby permitting the use of solvents that evaporatefaster. The more rapidly evaporating solvents, in turn, are more readilyremoved from the coating during the baking step after application ontothe plastic substrate, thereby reducing entrapment of solvent duringfinal curing that may detrimentally affect the barrier properties of thecoating.

Amine nitrogen content of the reaction products of the present inventionhas been found to relate directly to the barrier properties of thecoating composition. It is expedient to use polyamines that have greaterthan the amount of amine nitrogen intended for the final polymer sincereaction with the polyepoxide will dilute the amine nitrogen content.Therefore, the polyamine preferably has a plurality of secondary and/ortertiary amines in addition to the primary amine groups that are thepredominant reaction site for the reaction with the epoxy groups. Insome embodiments of the invention it has been found possible to furtherincrease the amine nitrogen content of the reaction product by using asthe polyepoxide reactant a polyepoxide having at least one amine group.Thus the polyepoxide contributes some amine to the final polymer ratherthan only diluting the amine content. The amine-containing polyepoxidemay be used to produce the prereacted adduct or as the curing agent toreact with the entire polyamine component. Using these preferredtechniques, amine nitrogen content of the reaction products can be madehigher than 10 percent, and in some cases as high as 14 percent orgreater, in which cases excellent barrier properties were found to beexhibited, particularly with respect to carbon dioxide.

Increasing hydroxyl group content of the polyamine-polyepoxide reactionproducts of the present invention has also been found to improve thebarrier properties. Reaction of the epoxy groups of the polyepoxidesnormally produces hydroxyl groups, but this aspect of the inventioncontemplates the use of particular reactants to provide additionalhydroxyl content to the reaction products beyond that normally resultingfrom the epoxy reactions. One approach is to employ a hydroxylcontaining epoxide such as glycidol. Another approach is to react analkanolamine with a polyepoxide having more than two epoxy groups permolecule in a preliminary step to react with some of the epoxy groups,leaving sufficient epoxy functionality to permit subsequent reactionwith the polyamine. The alkanolamines add not only hydroxyl groups tothe reaction product, but also additional amines. Yet another approachis to react the prereacted polyamine-polyepoxide adduct with apolyepoxide having more than two epoxy groups per molecule. In preferredembodiments, a polyepoxide having more than two epoxy groups permolecule that also includes amine groups is employed, thereby permittingthe hydroxyl content of the barrier film to be increased withoutsubstantially diluting the amine nitrogen content. In the basicembodiments of the present invention, the polymeric barrier materialtypically exhibits a hydroxyl content of about 6 weight percent based onthe total weight of the polymeric barrier material. Enhancements of thehydroxyl content in accordance with preferred embodiments may increasethe hydroxyl content to at least 10 weight percent.

One aspect of the preferred embodiments of the invention involves use ofpolyepoxides having more than two epoxy groups per molecule to producepolyamine-polyepoxide barrier coatings. As previously mentioned,additional epoxy groups provide sites for reaction with amine containingand/or hydroxyl containing compounds, such as the alkanolaminesmentioned above, while retaining sufficient unreacted epoxy groups forcrosslinking. Alternatively, polyepoxides having more than two epoxygroups per molecule may be used to produce the prereacted adduct,wherein a portion of the epoxy groups are initially reacted with anamine containing and/or hydroxyl containing compound (preferably analkanolamine) before reaction with a polyamine to form the adduct. Forthe sake of contributing to the amine nitrogen content of the barriercoating while providing the advantages of higher epoxy functionality, itis preferred that the polyepoxides having more than two epoxy groups permolecule also include amine groups. Barrier coatings in accordance withthe present invention in which the polyepoxide includes more than twoepoxy groups per molecule and also includes amine groups have been foundto have improved resistance to carbonating, i.e., to deteriorate due toexposure to carbon dioxide and water vapor in air. Additionally, ascuring agents for reacting with polyamines in the present invention, thehigher functional epoxies produce higher crosslink density in theresulting films. Higher crosslink density is associated with betterabrasion resistance and water resistance.

Additional improvements have been found to be yielded by including smallamounts of water in the final reaction mixture of polyamines andpolyepoxides. Not only does the water serve the expected function ofaccelerating the curing rate, but also the barrier properties of theresulting film surprisingly are substantially improved, particularlywith regard to carbon dioxide.

It is an additional advantage that the cured barrier coatings of thepresent invention are thermosetting polymers. This is preferred for foodand beverage containers so that rubbing of adjacent containers duringtransit does not cause localized softening of the barrier coatings andpossible damage to the coating. The cured barrier coatings of thepresent invention are also characterized as being relatively moistureinsensitive.

In further accordance with the present invention, a packaging materialis provided which includes at least one layer of a relativelygas-permeable polymeric material and at least one layer of apolyamine-polyepoxide barrier material characterized as containing atleast about seven percent by weight amine nitrogen, based on totalweight of the barrier material. The composite packaging materialexhibits oxygen permeability of less than about 1.5 cc-mil/100 in²-day-atmosphere and carbon dioxide permeability of less than about 15cc-mil/100 in² -day-atmosphere at 23° C. and zero percent relativehumidity. The barrier material included in the packaging material is afilm produced by applying to the polymeric material the coatingcompositions described above. Containers may be formed from thiscomposite packaging material.

In still another aspect of the present invention, a container isprovided which includes at least one layer of a relatively gas-permeablepolymeric material and at least one layer of the barrier coating aspreviously described.

DETAILED DESCRIPTION OF THE INVENTION

By the term "barrier material" as used throughout this description ismeant that such a material has a low permeability to gases such asoxygen and/or carbon dioxide, i.e., the material exhibits a highresistance to the passage of oxygen or carbon dioxide through thematerial. Permeation through a material is a function of the thicknessof the material. The barrier materials of the present invention exhibita combination of relatively high resistance to both carbon dioxide andoxygen, but many applications do not require resistance to both.Therefore, low permeability to either carbon dioxide or oxygen asdefined below is sufficient to qualify the material as a "barriermaterial." Embodiments of barrier materials of the present inventionintended primarily as oxygen barriers exhibit an oxygen permeability ofless than about 1.5, preferably less than about 1.0, and more preferablyless than about 0.5 measured as cubic centimeters of oxygen gaspermeating a one-mil thick sample, 100 inches square over a 24-hourperiod under an oxygen partial pressure differential of one atmosphereat 23° C. and at a relative humidity of zero. Barrier materials of thepresent invention intended primarily as carbon dioxide barriers exhibita carbon dioxide permeability of less than about 15.0, preferably lessthan about 5.0, and more preferably less than about 2.0 measured ascubic centimeters of carbon dioxide gas permeating a one-mil thicksample, 100 inches square over a 24-hour period under a carbon dioxidepartial pressure differential of one atmosphere at 23° C. and at arelative humidity of zero. Generally, it has been found that as theamount of amine nitrogen in a barrier material increases, gaspermeability decreases. Barrier materials having at least about sevenpercent by weight amine nitrogen can generally be further characterizedas exhibiting the permeability levels described above with regard tooxygen and/or carbon dioxide In addition, it may sometimes be consideredadvantageous for barrier materials also to have low permeabilities toorganic liquids and solvents, e.g., gasoline, toluene, methylenechloride, methyl ethyl ketone, methanol and the like.

A wide variety of polyepoxides may be utilized to react with polyaminesto form the barrier coating composition of the present invention. Thepolyepoxides may be saturated or unsaturated, aliphatic, cycloaliphatic,aromatic, or heterocyclic and may be substituted, if desired, withnoninterfering substituents such as hydroxyl groups or the like.

Examples of useful polyepoxides are polyglycidyl ethers of aromaticpolyols, e.g., polyphenols. Such polyepoxides can be produced, forexample, by etherification of an aromatic polyol with epichlorohydrin ordichlorohydrin in the presence of an alkali. The aromatic polyol may be,e.g., bis(4-hydroxyphenyl)-2,2-propane (generally known as bisphenol A),bis(4-hydroxyphenyl)-1,1-ethane, bis(4-hydroxyphenyl)-1,1-isobutane,bis(4-hydroxytertiarybutylphenyl)-2,2-propane,bis(2-hydroxynaphthyl)methane, 4,4'-dihydroxybenzophenone,1,5-dihydroxy-naphthalene and the like. Bisphenol A is the preferredaromatic polyol in preparation of the polyepoxide.

Also suitable as the polyepoxide are polyglycidyl ethers of polyhydricaliphatic alcohols such as 1,2-ethanediol, 1,2-propanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol,triethylene glycol, polyethylene glycol, polypropylene glycol and thelike. Similarly, the polyhydric aliphatic alcohols may be a hydrogenatedpolyphenol such as 2,2-bis(4-hydroxycyclohexyl)propane and the like. Thepolyglycidyl ether of 1,4-butanediol is preferred from among those ofpolyhydric alcohols. Blends of various polyepoxides, e.g., blends ofpolyepoxides of aromatic polyols and aliphatic polyols, may also beused.

Generally, the polyepoxides usually have molecular weights above about86, preferably from about 200 to about 700, and more preferably fromabout 200 to about 400, and have epoxy equivalent weights of above about43, preferably from about 100 to about 350, and more preferably fromabout 100 to about 200. The equivalent weight of the polyepoxide ispreferably minimized thereby increasing the amine nitrogen content ofthe resultant barrier material.

Further, a blend of a monoepoxide and a polyepoxide may be reactedinforming the ungelled amine-functional polymeric resin or a monoepoxidecan be reacted with the ungelled polymeric resin after its preparationfrom a polyamine and a polyepoxide thereby reducing the amount of aminefunctionality of the resin. Suitable monoepoxides include monoepoxidessuch as, e.g., a C₁₆ alpha olefin epoxide, 2-ethylhexylglycidyl ether,butylglycidyl ether, cresyl glycidyl ether, phenyl glycidyl ether(1,2-epoxy-3-phenoxypropane), propylene oxide, ethylene oxide, glycidol(2,3-epoxy-1-propanol) and the like.

Preferably, the polyepoxide used in forming the reaction product has anaverage 1,2-epoxy functionality of at least about 1.4 and mostpreferably about 2.0 or greater, i.e., the polyepoxide is a diepoxide.The diglycidyl ethers of an aromatic polyol such as bisphenol A or analiphatic alcohol such as 1,4-butanediol are the suitable polyepoxidesto react with the polyamine. Trifunctional and tetrafunctionalpolyepoxides are also useful in the present invention, and particularlyadvantageous are those that include amine groups, thereby increasing theamine nitrogen content of the barrier coating. Examples ofamine-containing tetrafunctional polyepoxides include N,N,N',N' tetrakis(oxiranylmethyl) 1,3 benzene dimethanamine (available as "TETRAD X" fromMitsubishi Gas Chemical Co.); N,N,N',N' tetrakis (oxiranylmethyl) 1,3cyclohexane dimethanamine (available as "TETRAD C" from Mitsubishi GasChemical Co.); and tetra glycidyl bis(para-amino phenyl) methane(available as "MY-720" from Ciba-Geigy). Other amine-containingpolyepoxides include diglycidyl aniline and triglycidyl aminophenol.

Polyoxalates or other suitable polycarboxalates may function in a mannersimilar to polyepoxide in the context of the present invention.Accordingly, although polyepoxides are preferred, polyoxalates and someother polycarboxalates may be considered as equivalent to polyepoxidesand should not be considered as being precluded from the scope of theinvention by the use of the term "polyepoxide" herein. Amongpolyoxalates that may be considered for use in the present invention asa partial or entire substitute for polyepoxide are poly(diallyloxalate), poly(hexanediol oxalate), poly(ethylene oxalate),poly(tetramethylene oxalate), diethyl oxalate-ethylene glycol polymer,poly(tetramethylene oxalate), poly(vinyl oxalate), polyethylene glycoloxalate and the like. Further, the esters of oxalic acid, such asdiethyl oxalate, dibutyl oxalate and the like, are considered to beuseful "polyoxalates" as the term is used herein. Esters of otherdicarboxylic acids, such as malonic acid, succinic acid and the like,may also be utilized in the compositions as long as the final productcontains the sufficient level of amine nitrogen.

The polyamine used in reacting with the polyepoxide generally has up toabout two primary amino nitrogen groups per molecule but preferably mayalso have secondary or tertiary amino nitrogen groups. Polyamines withless than two primary amino nitrogen groups per molecule may be used solong as sufficient secondary amino nitrogen groups are present.Preferred polyamines include aliphatic polyamines of the formula (R')₂N--R(NH--R)_(n) N(R')₂ wherein R is a C₂ to C₆ alkylene group,preferably a C₂ to C₄ alkylene group such as ethylene, isopropylene andthe like, R' is a hydrogen, a lower alkyl group such as methyl, ethyland the like, or a hydroxyalkyl group wherein the alkyl group containsfrom about one to four carbon atoms, and n is an integer from 0 to about10, preferably from about 1 to about 5 with the proviso that thepolyamine contains at least three secondary or primary amine hydrogens.Suitable examples of such polyamines include ethylenediamine,diethylenetriamine, triethylenetetramine, tetraethylenepentamine,N-hydroxyethyl ethylenediamine, N-hydroxyethyl diethylenetriamine,N,N-dihydroxyethyl diethylenetriamine and the like. The polyamine mayalso be an aromatic polyamine such as para-diaminobenzene,4,4'-diaminophenylaniline and the like. The polyamine may also be aketone blocked polyamine, sometimes referred to as a ketimine, e.g., apolyamine, such as tetraethylenepentamine,may be reacted with a ketone,such as methyl isobutyl ketone and the like, to give a polyamine havingthe primary amine groups blocked and three remaining reactive secondaryamine groups. Diprimary amine group-containing polyamines are generallypreferred, triethylenetetramine and tetraethylenepentamine are morepreferred polyamines, and tetraethylenepentamine is the most preferredpolyamine in the reaction to form the ungelled amine-functionalpolymeric resin.

Ammonia may also be a precursor to a suitable polyamine, e.g., two molesof ammonia may be reacted with one mole of a suitable diepoxide, such asa diglycidyl ether of bisphenol A, to produce a diprimaryamine-functional material useful in forming the resin of the presentinvention. The polyamine may also be polyethyleneimine and the like.Still further, the polyamine may also be a polyoxyalkylene-polyaminesuch as the material described in U.S. Pat. No. 4,423,166 forpreparation of an ungelled material used in electrodeposition. Theresultant ungelled resin should contain the sufficient amine nitrogencontent. Preferably, such a product of a polyoxyalkylene-polyamine and,e.g., a polyepoxide, may derive from polyamines including greater thantwo amine nitrogen groups per molecule but only up to about two primaryamino nitrogen groups per molecule.

The polymeric resins of the present invention as well as the polyepoxideand polyamine reactants from which they are made preferably have minimalcontent of extraneous groups that would dilute the amine nitrogencontent or hydroxyl content of the barrier coating on a percent weightbasis. For example, the reactants and the polymers of the presentinvention are preferably free of oxyalkylene moieties and otherextraneous moieties. Extraneous groups whose inclusion is preferablyavoided include any group other than amine, hydroxyl, or epoxy.Excessively long chain alkyl groups are also preferably avoided for thesame reason.

A polyacrylate may be used in forming the prereacted adduct, i.e., anungelled amine-functional polymeric resin. Such a polyacrylate may be apolyacrylate ester of a polyol or a polymethacrylate ester of a polyol,such esters containing at least two terminal acrylate or methacrylategroups per molecule. Such esters include the acrylic acid andmethacrylic acid esters of aliphatic polyhydric alcohols, preferablydihydric alcohols. Such alcohols may be, e.g., alkylene glycols such as1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and thelike, or polyalkylene glycols such as diethylene glycol, triethyleneglycol, tetraethylene glycol and the like. Typical compounds include,e.g., 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate,1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, triethyleneglycol diacrylate, triethylene glycol dimethacrylate and the like.

The reactive sites on the polyamines for reacting with the polyepoxidesare the active amine hydrogens. In general, the amounts of the reactantsmay be chosen so as to provide a ratio of active amine hydrogens in thepolyamine to epoxy groups in the polyepoxide in a ratio that ranges from1:0.1 to 1:1 on a molecular weight basis. Preferably the ratio rangesfrom 1:0.2 to 1:0.8. Maximizing the amount of polyamine is generallydesirable for the sake of maximizing the amine nitrogen content of thebarrier coating, but insufficient numbers of epoxy groups may notprovide enough crosslinking to yield a strong, moisture resistant,solvent resistant film. Larger numbers of epoxy groups could in theorybe used, but to do so would be contrary to the objective of maximizingthe amine nitrogen content of the barrier coating since the excess epoxywould dilute the amine nitrogen content of the product. Also, the use ofmore epoxy than required can produce excessive crosslinking and a filmthat is too brittle. Even in the embodiments that use amine-containingpolyepoxides, the amine nitrogen content of the polyepoxide is usuallylower than that of the polyamine, so that excessive use of thatpolyepoxide would still tend to dilute the amine nitrogen content of theproduct. In those embodiment in which the polyamine is prereacted with aportion of the polyepoxide to form an adduct, approximately 10 to 80percent, preferably 20 to 50 percent, of the active amine hydrogens ofthe polyamine may be reacted with epoxy groups during formation of theadduct. Prereacting fewer of the active amine hydrogens reduces theeffectiveness of the prereaction step and provides little of thelinearity in the polymer product that is one of the advantages offorming the adduct. Prereacting larger portions of the active aminehydrogens is not preferred because sufficient active amine hydrogengroups must be left unreacted so as to provide reaction sites forreacting with the remainder of the polyepoxide during the final curingstep. Furthermore, in making the adduct it is also desirable to minimizethe amount of polyepoxy used in order to avoid diluting the aminenitrogen content of the final polymer.

Those embodiments that include a polyacrylate or polyoxalate in thecomposition are preferably reacted at or near stoichiometric ratios ofactive amine hydrogens to epoxy groups.

In forming the barrier coating from the reaction of an adduct with apolyepoxide, the two components are preferably reacted together at aratio of active amine hydrogens to epoxy groups of from about 1:0.1 toabout 1:1, more preferably from about 1:0.2 to about 1:0.85, mostpreferably from about 1:0.3 to about 1:0.7. That is, the barriermaterial can include up to one epoxy equivalent per one amineequivalent. Each amine hydrogen of the amine-functional adduct istheoretically able to react with one epoxy group and is considered asone amine equivalent. Thus, a primary amine nitrogen is considered asdifunctional in the reaction with polyepoxides to form the barriermaterial. Preferably, the reaction product contains an excess of aminehydrogen equivalents over epoxy equivalents, which provides theadvantage of keeping the weight percentage of amine nitrogen in thereaction product higher thereby providing lower gas permeabilities. Asstated before, the use of larger amounts of epoxy is not strictlyprecluded but generally is counterproductive. On the other hand,providing fewer epoxy groups during the curing stage may not yieldsufficient crosslinking to produce a durable film.

Preparation of a prereacted adduct, comprising an ungelled,amine-functional, polymeric resin involves the slow addition of thepolyepoxide, preferably a dilute polyepoxide solution, to a dilutepolyamine solution at temperatures and over time sufficient to form theungelled amine-functional polymeric resin. Preparation of such anungelled amine-functional polymeric adduct is described in commonlyassigned application Ser. No. 07/375,659, entitled "UngelledPolyamine-Polyepoxide Resined" by Nugent et al., filed on Jun. 30, 1989,now U.S. Pat. No. 5,006,381, and the description of the preparation ofsuch an ungelled resin is incorporated herein by reference. The reactionof the polyepoxide and the polyamine to give the ungelled adduct iscarried out at temperatures and concentrations of reactants sufficientto obtain the ungelled product and may vary depending upon selection ofstarting materials. Generally, reaction temperatures may vary from about40° C. to 140° C., with lower temperatures (40° C. to 110° C.) beingpreferred for systems susceptible to gelation. Similarly, concentrationsof reactants may vary from neat to as low as five percent by weight ofreactant in an appropriate solvent depending upon the particular molarratio and type of reactants. Lower concentrations will generally berequired for systems susceptible to gelation. Specific reactionconditions may be readily chosen by one skilled in take art.

The ungelled amine-functional polymeric adducts are described throughoutthis specification as containing an average of greater than twopolyamine moistly within said resin. By "polyamine moiety" is meant thatportion of a polyamine molecule which remains after reaction with thepolyfunctional material. Thus, the ungelled polymeric resins contain anaverage of greater than two separate polyamine portions. An examplewould be the product of four mole of a diprimary amine-containingpolyamine reacted with three moles of a diepoxide, such a productcontaining an average of about four polyamine moieties.

By the term "ungelled" as used throughout this description is meant thatsuch an amine-functional polymeric resin is a soluble or dispersiblereaction product, the resin being fluid under processing conditions ofthe present invention.

With the prereacted adduct approach, additional polyepoxide can bereacted with the adduct to give a cured thermoset product. Generally,such a polyepoxide may be the same as those polyepoxides previouslydescribed for forming the adduct. Polyoxalates may be utilized to reactwith the adduct instead of polyepoxides to give the cured product, thepolyoxalates containing at least two reactive functional groups. Suchpolyoxalates may be the same as those described for prereaction to formthe ungelled adduct.

A monoepoxide, such as a C₁₆ alpha olefin epoxide, 2-ethylhexylglycidylether, butylglycidyl ether, cresyl glycidyl ether, phenyl glycidyl ether(1,2-epoxy-3-phenoxypropane), propylenes oxide, ethylene oxide, glycidol(2,3-epoxy-1-propanol) and the like, may also be included with thepolyepoxide or polyoxalate in the coating compositions as long as asufficient amount of polyepoxide or polyoxalate is also present toprovide for crosslinking and cure upon heating.

While certain advantages are obtained from proreacting polyamine withpolyepoxide to form an adduct, other advantages result from a singlestep reaction of polyamine with all of the polyepoxide required to formthe barrier coating of the present invention. In this embodiment,molecular weights of the resins are kept relatively low, therebyproviding relatively low viscosity without requiring as much solvent. Asa result, compositions suitable for application by spraying or rollcoating can be provided with low volatile organic content (VOC). Barriercoating compositions can be provided by this embodiment having solidscontents greater than 50 percent by weight, typically in the range of 50to 70 percent solids, although even higher solids contents are possible.If the polyepoxide and polyamine reactants are sufficiently low inmolecular weight, solvents may be omitted. Another advantage is that itis believed that better barrier properties may be attainable withcoating compositions having lower solvent content due to lower tendencyto trap solvent in the cured film. This is also aided by the ability touse faster evaporating solvents in this embodiment. High solidscompositions are also an advantage for the sake of attaining the desiredcoating thickness in less time on high speed coating lines. Inclusion ofa flow control agent such as the siloxanes disclosed herein is preferredin the high solids embodiments to assure pin hole free coatings.

In the one-step reaction embodiment, no substantial proreaction isinvolved, but initiation of the reaction of the polyepoxide with thepolyamine is delayed during an ingestion period of about 30 to 60minutes at room temperature following mixing of the two reactivecomponents and before the composition is applied onto the substrate.Some minor reaction may occur during this ingestion period, but the timedelay is required before significant reaction takes place. After theingestion period the mixture has a pot life typically on the order of 1to 2 hours before it hardens, depending upon the particular composition.Curing times and temperatures are essentially the same for thisembodiment as for the adduct embodiments.

Solvents for use in the composition of the present invention must becompatible with the plastic substrates being coated and should be chosenso as to provide desirable flow properties to the liquid compositionupon application. Suitable solvents for use with the compositions of thepresent invention are preferably oxygenated solvents, such as glycolethers, e.g., 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol,2-butoxyethanol, 1-methoxy-2-propanol and the like, or alcohols such asmethanol, ethanol, propanol and the like. Glycol ethers, such as2-butoxyethanol and 1-methoxy-2-propanol, are more preferred with1-methoxy-2-propanol being most preferred. The use of1-methoxy-2-propanol is preferred for its lower flash point, whichminimizes solvent retention in the cured film, and its use isparticularly suitable with the embodiments involving relatively lowmolecular weight reactants, particularly those not involving aprereacted adduct. In order to obtain desired flow characteristics insome of the embodiments using a prereacted adduct, use of2-butoxyethanol may be preferred. In embodiments not requiring slowevaporating solvents for the sake of flow properties, the solventslisted here may be diluted with less costly solvents such as toluene orxylene. The solvent may also be a halogenated hydrocarbon, for example,a chlorinated hydrocarbon, such as methylene chloride,1,1,1-trichloroethane and the like (usually considered fast evaporatingsolvents), may be especially useful in obtaining cured barrier films.Mixtures of such solvents may also be employed. Non-halogenated solventsare preferred where the resultant barrier material is desired to behalide-free. The resin may also be in an aqueous medium, i.e., theungelled amine-functional polymeric resin may be an aqueous solution ordispersion. For example, when the polyepoxide used in forming thereaction product is a water-soluble polyepoxide, e.g., the polyglycidylether of an aliphatic diol such as butanediol, the ungelledamine-functional polymeric resin can be utilized as an aqueous solution.Otherwise, with water-insoluble polyepoxides, the ungelledamine-functional polymeric resin can have sufficient amine groupsneutralized with an organic acid, such as formic acid, lactic acid, oracetic acid, or with an inorganic acid, such as hydrochloric acid orphosphoric acid, to allow solubilization of the ungelledamine-functional polymeric resin in an aqueous medium. An organic acidis preferably used.

Reaction of a polyepoxide and a polyamine produces resin polymers havinga plurality of amine and hydroxyl functionalities, both of which appearto contribute to the barrier properties attained by the presentinvention. Thus, selecting the polyepoxide and polyamine reactants inorder to maximize the amine and hydroxyl functionalities is generallydesirable, but increasing the content of one without decreasing thecontent of the other can be a problem. One approach is to selectpolyamine and polyepoxide reactants having relatively large numbers ofamine and epoxy groups respectively relative to the number of carbonatoms per molecule. Another approach is to employ polyepoxides havingmore than two epoxy groups per molecule, thereby increasing the numberof hydroxyl groups per molecule resulting from reaction of the epoxygroups. Additionally, it is advantageous to select a polyepoxide thatincludes amine functionality as well, examples of which have beendisclosed above. Reaction of an epoxy group produces a hydroxyl group,but additional hydroxyl functionality can be contributed to the reactionproduct by reactants that already include hydroxyl groups. Glycidol,disclosed as one of the epoxides that may be used in the presentinvention falls into this category, but is relatively costly. A morepractical approach has been found to be the inclusion of analkanolamine, such as diethanolamine, as an additional reactant. Thealkanolamine may be included in sufficient quantity to react with aportion of the epoxy groups of the polyepoxide, thereby adding bothamine and hydroxyl groups to the reaction product, leaving some of theepoxy groups unreacted and available for reaction with the polyamine orthe amine functional adduct. Larger alkanolamines than diethanolaminemay be used, but it is preferred to keep the carbon content low so as tonot dilute the amine and hydroxyl concentrations in the final reactionproduct. Polyepoxides having more than two epoxy groups per molecule arepreferred for reacting with alkanolamines, whereby the reaction with thealkanolamine can be effected while leaving diepoxy functionality forsubsequent crosslinking with the polyamine or adduct. Use ofalkanolamines in this manner was found to yield substantial reductionsin oxygen permeability and particularly significant reductions in carbondioxide permeability.

The present invention is further concerned with packaging materials andcontainers formed of a barrier material or packaging materials andcontainers including a barrier material. Such packaging materials and/orcontainers would be desired to have some or all of the followingproperties:(1) low oxygen permeability, e.g., for the protection ofpackage contents such as food from external oxygen, (2) low carbondioxide permeability, e.g., for the retention of carbon dioxide gaswithin a container, (3) good adhesion to gas-permeable polymericmaterials used in forming multilayer packaging materials or multilayercontainers, (4) retortability, i.e., the ability to withstand wetautoclaving at temperatures up to about 130° C. (the temperature ofsaturated steam), without blushing, loss of oxygen or carbon dioxideimpermeability, or loss of adhesion, (5) good flexibility, (6) highimpact resistance, (7) low processing and cure temperatures for use withheat-sensitive substrates, e.g., certain gas-permeable polymericmaterials, (8) high gloss, and (9) good clarity. In addition, thebarrier materials utilized in packaging materials or containers of thisinvention can be and are preferably characterized as halide-free.

In the packaging materials and containers of the present invention,barrier materials formed from the coating compositions of the presentinvention may be used in combination with any polymeric material used inconventional packaging materials and containers, e.g., polyolefins suchas polyethylene or polypropylene, polyesters such as poly(ethyleneterephthalate), polycarbonates and the like. Many polymeric materials,such as, e.g., polyolefins and polycarbonates, are known to be verygas-permeable. The term "gas-permeable" is used herein to mean that sucha polymeric material has a gas permeability greater than that of thebarrier materials. Gas-permeable polymeric materials are generally morelimited for use as packaging of oxygen-sensitive foods or beverages, orfor packaging of carbonated beverages. The herein described barriermaterials are especially suitable for use in combination with polymericmaterials such as polyolefins or polycarbonates. Polyolefins andpolycarbonate materials have both high oxygen permeabilities and carbondioxide permeabilities, i.e., values generally greater than 100 cubiccentimeters (cc) of oxygen and greater than 250 cc of carbon dioxidepermeating a one-mil thick sample, 100 inches square over a 24-hourperiod under an oxygen or carbon dioxide partial pressure differentialrespectively of one atmosphere (100 cc-mil/100 in² -day-atmosphere) at23° C. and a relative humidity of zero. The containers or packagingmaterials of this invention may also incorporate one or more otherpolymeric materials such as, e.g., polyvinylidene chloride,polyacrylonitrile, polystyrene, acrylonitrile-styrene copolymers,polyamides, polyfluorocarbons, and blends or other combinations of suchmaterials.

The barrier materials can be applied as either solvent or aqueous-basedthermosetting coating compositions onto other polymeric materials, e.g.,packaging materials or containers, by any conventional means such asspraying, rolling, dipping, brushing and the like. Spray applications orroll applications are preferred. For example, conventional spraytechniques and equipment for applying curable coating components can beutilized.

Generally, the solution of the amine-functional polymeric resin readyfor application will have a weight percent of resin solids in the rangeof from about 15 percent by weight to about 50 percent by weight,preferably from about 25 to about 40 percent by weight for embodimentsemploying the prereacted adduct approach. Higher weight percent solidsmay present application difficulties, particularly with sprayapplication, while lower weight percentages will require removal ofgreater amounts of solvent during a heat-curing stage. For theembodiments using direct reaction of the polyamine and polyepoxide,solids contents above 50 percent can be applied successfully.

The amine-functional polymeric resin should contain sufficient aminefunctionality so that the barrier coating will contain at least aboutseven percent by weight amine nitrogen, and preferably at least aboutten percent by weight amine nitrogen as described hereinabove. While notwishing to be bound by theory, it is believed that greater levels ofamine nitrogen in the barrier material contributes to adhesion of thebarrier materials to other polymeric materials, e.g., gas-permeablepolymeric materials.

Coating compositions of this invention can further include otheradditives including pigments, catalysts for coating compositions whichinvolve an epoxy-amine reaction, silicones or surfactants. For example,the addition of pigments can further reduce the gas permeability of theresultant barrier material. Among the useful pigments in decreasing thegas permeabilities may be included titanium dioxide, micas, silicapigments, talc and aluminum or glass particulates, e.g., flakes. Micas,aluminum flakes and glass flakes may be preferred due to a plate-likestructure of such pigments. Generally, when pigments are included in thecoating compositions, the weight ratio of pigment to binder is about1:1, preferably about 0.3:1, is and more preferably about 0.05:1, thebinder weight being the total solids weight of the polyamine-polyepoxideresin in the coating composition.

Silicones may be included in coating compositions of this invention toassist in wetting of gas-permeable polymeric surfaces. Suitablesilicones include various organosiloxanes such as polydimethylsiloxane,polymethylphenylsiloxane and the like. Exemplary are SF-1023 silicone (apolymethylphenylsiloxane available from General Electric Co.), AF-70silicone (a polydimethylsiloxane available from General Electric Co.),and DF-100 S silicone (a polydimethylsiloxane available from MazerChemicals, a division of PPG Industries, Inc.) Such silicones may beadded to the coating compositions in amounts of from about 0.01 to about1.0 percent by weight based on total resin solids in the composition.

Surfactants may be included in aqueous-based coating compositions of thepresent invention, such as when the ungelled amine-functional polymericresins are in aqueous solution. Such surfactants may generally be anysuitable nonionic or anionic surfactant and may be employed at levels ofabout 0.01 to about 1 percent by weight basis total weight of thesolution.

Among the catalysts which may be included in the coating compositionsare those generally used for epoxy-amine reactants such as dihydroxyaromatics (e.g., resorcinol), triphenyl phosphite, calcium nitrate andthe like.

When the composition includes pigments and additives, it is desirablefor the polyamine-polyepoxide resin in the formulation to containsufficient amine nitrogen such that the amine nitrogen content as aweight percent basis of the total weight of solids in the composition isat least 7 percent_(s) preferably at least 10 percent.

In application of a thermosetting coating composition onto a substrateto form a layer of a barrier material, the components of a coatingcomposition, e.g., a polyepoxide and the ungelled amine-functionalpolymeric resin, are first thoroughly mixed and then applied byappropriate means such as spraying. After mixing, the coatingcomposition can also be held for a period of time (referred to as aningestion time) from about 5 minutes to about 60 minutes prior toapplication to improve cure and clarity. This ingestion time cangenerally be eliminated when the polyamine is a prereacted adduct ofpolyepoxide and polyamine or when the solvent is 2-butoxyethanol. Afterapplication of the coating composition, it may be cured at temperaturesas low as ambient temperature, i.e., about 70° F., by allowing for agradual cure over several hours to several days or longer. However, suchlow temperature curing is slower than-desired for commercial productionlines and is not as efficient in removing solvent from the curedcoating. Therefore, it is preferred that the coating be cured by heatingat elevated temperatures as high as possible without distorting theplastic substrates and sufficiently high to effectively drive theparticular solvent from the coating. For a relatively "slow" solvent,that is, a solvent having a flash point around 140° F. or higher,temperatures from about 130° Fahrenheit (F) to about 230° F., preferablyfrom about 160° F. to about 200° F. for from about 1 minute to about 60minutes may be suitable. For relatively "fast" solvent, that is, asolvent having a flash point below about 120° F., temperatures in therange of 100° F. to 160° F., preferably from about 120° F. to 150° F.,may be suitable. The thermosetting coating composition may be appliedand cured as a single layer or may be applied as multiple layers withmultiple heating stages to remove solvent from each subsequent layer.

Multilayer packaging materials of the present invention comprise atleast one layer of a gas-permeable polymeric material and at least onelayer of a barrier material that is the reaction product of apolyepoxide and a polyamine as described herein and characterized ascontaining at least about seven percent amine nitrogen. In thepreparation of the multilayer packaging material, a layer of thegas-permeable polymeric material can be coated with a layer of thebarrier material composition, e.g., by roll coating or spraying, and thelayer of the coating compositions can then be cured to form thethermoset barrier layer by heating for a sufficient time at sufficienttemperatures. The heating temperatures will generally be beneath thetemperature at which the gas-permeable polymeric material suffers anydetrimental effects, such as distortion, discoloration or degradation.Generally, the coating composition can be cured to the resultantthermoset layer by heating at elevated temperatures as describedpreviously.

In another embodiment of the invention, a laminate including a barrierlayer may be formed, e.g., by spray application of the coatingcomposition onto a first layer of a gas-permeable polymeric material.Thereafter, a second layer of a similar or dissimilar gas-permeablepolymeric material may be applied over the barrier layer to form alaminate and heated as previously described or optionally heated underpressure. For example, such a laminate may be pressed under pressures offrom about 5 to about 200 pounds per square inch (psi).

In a preferred embodiment of a multilayer packaging material inaccordance with the present invention, polypropylene is thegas-permeable polymeric material. The surface of the polypropylene (orany other polyolefin) is preferably treated to increase surface tensionby, e.g., flame-treating, corona-treating and the like, all of which arewell known to those skilled in the art. Such treatments are described indetail by Pinnet etal. in Plastics; Surface and Finish, Butterworth &Co. Ltd. (1971), Chapter 3, on surface treatments for plastic films andcontainers, and this description of surface treatments is hereinincorporated by reference. Such treatments promote better adhesion ofthe barrier layer to polyolefin material.

The barrier layer in this example is formed upon the treatedpolypropylene from a coating composition including, e.g., a polyepoxidesuch as a diglycidyl ether of bisphenol A as one component and, as asecond component, a solution containing about 20 percent by weight of anungelled amine-functional polymeric resin comprised of the reactionproduct of a diglycidyl ether of bisphenol A and tetraethylenepentamine,such ungelled amine-functional polymeric resin having a number averagemolecular weight of about 3600 and an amine nitrogen content of about13.7, based on total weight of solvent and resin in solution, thesolvent being 1-methoxy-2-propanol. The two-package coating compositionis mixed and either rolled or sprayed onto the treated polypropylene togive about a one-mil thick coating of the barrier material. The layer ofbarrier material coating is cured by heating at about 160° F. for about10 minutes.

The above-described multilayer packaging materials may be formed intocontainers by conventional plastic processing techniques. For example,sheets, films, and other structures may be formed by well knownlamination or extrusion techniques. Film or sheet material made from themultilayer packaging material may be formed into articles such aswrappers, bags and the like. Molded containers may be made from theabove-described packaging materials by blow molding the packagingmaterial or by other such molding techniques all of which are well-knownin the art.

Optionally, containers including at least one layer of a gas-permeablepolymeric packaging material can be pre-formed into any desired shapeand then at least one layer of a barrier coating of the presentinvention can be applied onto the preformed container in a similarmanner as described for the multilayer packaging materials. Themultilayer containers and multilayer packaging materials of the presentinvention are ideally suited for packaging of food, beverages, medicinesand like substances. The principal advantage of the packaging materialsand containers of this invention is the overall reduction in thetransport of gases through the container walls. To achieve thisreduction it is not necessary that the entire surface area of thecontainer be coated with the barrier material. The barrier materials ofthe preferred embodiments of the present invention are capable of suchsignificant reductions in permeability that coating, for example, onlyabout 50 percent or less of the container's surface area may yield amajor increase in self life of the product. Coating only a portion ofthe surface area is advantageous in that the coating process may besimplified by applying the barrier material only onto areas of thecontainer that are relatively easy to coat, such as the vertical sidewalls. The barrier material may also be limited to areas on thecontainer that are to be covered by a label or other opaque material,thereby lessening the appearance requirements for the barrier material.The lower the permeability of the uncoated packaging material, thesmaller the area that need be coated with the barrier material of thepresent invention. For example, containers of poly(ethyleneterephthalate) have sufficiently good barrier properties that they areparticularly suitable for partial coatings of the barrier material.

The multilayer packaging material and containers of the presentinvention do not require the use of adhesives, tie layers or the likebetween the respective gas-permeable polymeric materials and the barriermaterials.

While barrier materials of this invention have been described as usefulas coatings on a variety of gas permeable polymeric materials, it shouldbe readily apparent to those reading this specification that suchbarrier materials may be utilized otherwise than with gas permeablepolymeric materials and may be useful, e.g., as coatings on metalsurfaces where contact with, e.g., oxygen, is sought to be minimized.Such barrier materials may also be used without any other polymericmaterial. For example, such barrier materials may be formed into thinfilms such as those films commonly sold for home use storage of, e.g.,food items in refrigerators and/or freezers.

The present invention is more particularly described in the followingexamples which are intended as illustration only since numerousmodifications and variations will be apparent to those skilled in theart. Examples A-J describe the preparation of the ungelledamine-functional polymeric adducts that are polyamine-polyepoxidereaction products or polyamine-polyacrylate reaction products, whichadducts are subsequently cured to form the barrier materials by reactionwith additional polyepoxide.

TESTING PROCEDURES

Oxygen permeabilities, i.e., oxygen gas transmission rates throughplastic films, composites and/or laminates were determined in accordancewith ASTM D-3985-81.

Carbon dioxide permeabilities, i.e., carbon dioxide transmission ratesthrough plastic films, composites and/or laminates were determined usinga MULTI-TRAN 800 film permeation test system, available from ModernControls, Inc. (Minneapolis, Minn.). Such a test system utilizes athermal conductivity detector for gas sample analysis with helium as thecarrier gas. All test gases were dried via appropriate means so that thetest conditions were at zero percent relative humidity.

EXAMPLE A

An ungelled amine-functional polymeric resin (an epoxy-amine adduct),was prepared by the following procedure: A reaction vessel was chargedwith one mole (146 grams (g)) of triethylenetetramine (TETA) and 897 gof 1-methoxy-2-propanol, available from Dow Chemical Company as DOWANOLPM (14 percent by weight TETA in the total charge), and the admixturewas heated to 100° C. under a nitrogen atmosphere. A mixture of 0.85mole (320 g) of a diglycidyl ether of bisphenol A (available as EPON 828from Shell Chemical Corporation (molecular weight of 376.47)) and 1963 gof 1-methoxy-2-propanol was then gradually added over one hour. Thereaction mixture was held at 100° C. for two hours, followed by heatingat 110° C. to strip solvent. The resultant product had a theoreticalmolecular weight of about 3200, a percent solids as measured at 110° C.for one hour of 39.9 percent and a theoretical amine nitrogen content ofabout 12.3 percent basis total resin solids.

EXAMPLE B

Example A was repeated with the exception that 2-butoxyethanol was thesolvent. The unstripped product had a measured total solids of 15.1percent.

EXAMPLE C

An ungelled amine-functional polymeric adduct was prepared as follows: Areaction vessel was charged with 146 g of TETA and 584 g of1-methoxy-2-propanol, and the admixture was heated under nitrogen to100° C. A mixture of 172 g of a 1,4-diglycidyl ether of butanediol(available as ARALDITE RD-2 from Ciba-Geigy Corporation) and 687 g of1-methoxy-2-propanol was gradually added over one hour. The reactionmixture was held at 100° C. for two hours, followed by heating at 110°C. to strip solvent. The resultant product had a theoretical molecularweight of about 2200, a percent solids as measured at 110° C. for onehour of 29.2 percent and a theoretical amine nitrogen content of about17.8 percent basis total resin solids.

EXAMPLE D

Example C was repeated with the exceptions that 2-butoxyethanol was thesolvent and the amounts of materials were doubled. The unstrippedproduct had a measured total solids of 18.68 percent.

EXAMPLE E

An ungelled amine-functional polymeric adduct was prepared as follows: Areaction vessel was charged with 1.2 moles (123.6 g) ofdiethylenetriamine (DETA) and 700 g of 1-methoxy-2-propanol. Theadmixture was heated under nitrogen to 100° C. and a mixture of 1.02mole (384 g) of EPON 828, and 2173 g of 1-methoxy-2-propanol was addedover one hour. The reaction mixture was held at 100° C. for a total ofabout two hours, followed by heating at 110° C. to strip solvent. Theresultant product had a theoretical molecular weight of about 3000, apercent solids as measured at 110° C. for one hour of 32.5 percent and atheoretical amine nitrogen content of about 9.8 percent basis totalamine solids.

EXAMPLE F

Example E was repeated with the exception that 2-butoxyethanol was thesolvent. The unstripped product had a measured total solids of 15.31percent.

EXAMPLE G

An ungelled polymeric adduct was prepared as follows: A reaction vesselwas charged with 1 mole (189 g) of tetraethylenepentamine (TEPA) and1161 g of 1-methoxy-2-propanol. The admixture was heated under nitrogento 100° C., and a mixture of 0.857 mole (322.2 g) of EPON 828 epoxy and1979 g of 1-methoxy-2-propanol was added over one hour. The reactionmixture was then held at 100° C. for a total of about two hours,followed by vacuum stripping of solvent at about 80° C. The resultantproduct had a theoretical molecular weight of about 3600, a percentsolids as measured at 110° C. for one hour of 30.1 percent, atheoretical equivalent weight per amine hydrogen of 96.7 g and atheoretical amine nitrogen content of about 13.7 percent basis totalresin solids.

EXAMPLE H

Example G was repeated with the exception that 2-butoxyethanol was thesolvent. The unstripped product had a measured solids of 15.0 percent.

EXAMPLE I

An ungelled amine-functional polymeric resin (an amine-acrylate adduct)was prepared as follows: A reaction vessel was charged with 146 g ofTETA and 584 g of 2-butoxyethanol, and the admixture was heated undernitrogen to about 100° C. A mixture of 169.5 g of 1,6-hexanedioldiacrylate (0.75 mole) and 678 g of 2-butoxyethanol was gradually addedover one hour. The reaction mixture was held at 100° C. for two hours.The resultant product had a theoretical molecular weight of about 1262,a theoretical equivalent weight per amine hydrogen of 70.1, atheoretical amine nitrogen content of 17.7 percent, and a percent solidsas measured at 110° C. for one hour of 18.5 percent. Such anamine-acrylate adduct may be crosslinked with, e.g., a polyepoxide toyield a thermoset barrier material.

EXAMPLE J

An ungelled polymeric adduct was prepared as follows: A reaction vesselwas charged with 1 mole (189 g) of tetraethylenepentamine (TEPA) and1161 g of 1-methoxy-2-propanol. The admixture was heated under nitrogento 100° C., and a mixture of 0.857 mole (322.2 g) of EPON 828 epoxy and1979 g of 1-methoxy-2-propanol was added over one hour. The reactionmixture was then held at 100° C. for a total of about two hours,followed by vacuum stripping at about 80° C. The resultant product had apercent solids as measured at 110° C. for one hour of 25.2 percent, atheoretical equivalent weight per amine hydrogen of 96.7 g and atheoretical amine nitrogen content of about 13.7 percent basis totalresin solids.

This adduct was then reacted with a monoepoxide thereby reducing theamine equivalents in the product as follows: A total of 500 g of theadduct at 25.2 percent by weight resin solids in 1-methoxy-2-propanolwas charged into a reaction vessel equipped with a nitrogen sparge. Thecharge was heated to about 50° C., whereupon 28.9 g of glycidol wasslowly added dropwise while maintaining the resultant exotherm under100° C. After the glycidol addition was complete, the reaction mixturewas heated at 100° C. for one hour. The resultant product has a percentsolids as measured at 110° C. for one hour of 31.6 percent, atheoretical equivalent weight per amine hydrogen of 169.8 g and atheoretical amine nitrogen content of 11.1 percent basis total resinsolids.

Examples 1-8 illustrate the preparation of the thermoset barriermaterials having varying degrees of gas barrier properties. Example 9illustrates the solvent barrier properties of the thermoset barriermaterials.

EXAMPLE 1

Barrier materials were coated onto a polypropylene sheet at variousequivalent ratios of polyepoxide to amine-functional material.

EXAMPLE 1a

A one-mil thick film of polypropylene with one corona-treated surfacehaving a surface tension of about 40 to 42 dynes/centimeter (availablefrom Phillips Joanna, a division of Joanna Western Mills Company asPJX-2135 polypropylene film) was coated with a two-package coatingcomposition including: (1) the ungelled amine-functional polymericadduct from Example G and (2) a diglycidyl ether of bisphenol A havingan epoxy equivalent weight of about 188 (available as EPON 828 fromShell Chemical Company). The ungelled amine-functional polymeric adduct(75 grams total of a 30.1 percent by weight resin solution in1-methoxy-2-propanol) was stirred with a high-intensity mixer as 43.9 gof EPON 828 epoxy was added. The equivalent ratio of epoxy groups toamine hydrogen equivalents in this mixture was about 1:1. The mixturewas held for 20 minutes and then about a one-mil thick coating layer wasdrawn down by a roll bar onto the treated surface of the polypropylene.The coated film was heated at 160° F. (about 71° C.) for 20 minutes andyielded a flexible, clear film of the barrier material having a highgloss. The coated film was tested for oxygen and carbon dioxidepermeabilities and the results are given in Table 1.

EXAMPLE 1b

A one-mil thick film of polypropylene as in Example 1a was coated withthe two-package coating composition as above except the amount of EPON828 epoxy was reduced to 23.7 g. The equivalent ratio of epoxy groups toamine hydrogen equivalents in this mixture was 0.54:1. The coated film,drawn down and heated as above, yielded a flexible, clear film of thebarrier material having a high gloss. A sample of this coating sprayedonto a titanium dioxide-pigmented polypropylene substrate at a thicknessof about 0.8 to about 1.0 mils and heated for 20 minutes at 160° F. hada gloss of 40 to 45 percent at 20° and of 100 to 110 percent at 60° incomparison to 9 percent and 30 percent respectively for the uncoatedpolypropylene substrate. Gloss measurements were made with gloss metersmanufactured by the Gardner Instrument Company. The results of testingfor oxygen and carbon dioxide permeabilities are given in Table 1.

EXAMPLE 1c

A one-mil thick film of polypropylene as in Example 1a was coated withthe two-package coating composition as above except the amount of EPON828 epoxy was reduced to 11.86 g. The equivalent ratio of epoxy groupsto amine hydrogen equivalents in this mixture was 0.27:1. The coatedfilm, drawn down and heated as above, yielded a flexible, clear film ofthe barrier material having a high gloss. The results of testing aregiven in Table 1.

EXAMPLE 1d

A one-mil thick film of polypropylene as in Example 1a was coated with atwo-package coating composition including: (1) an ungelledamine-functional polymeric adduct similar to that of Example G and (2)EPON 828 epoxy. The ungelled amine-functional polymeric adduct (50 gtotal of a 28.0 percent by weight resin solution in1-methoxy-2-propanol) was stirred with a high-intensity mixer as 3.67 gof EPON 828 epoxy was added, followed by addition of 0.088 g (0.5percent by weight on total resin solids in solution) ofpolydimethylsiloxane (available as SF-1023 from General Electric Go.)The equivalent ratio of epoxy groups to amine hydrogen equivalents inthis mixture was about 0,135:1. The mixture was applied and heated as inExample 1a except two layers, each about 0.4 to 0.5 mils thick, weresequentially drawn down and heated. The resultant barrier film wasclear, flexible and had a high gloss. The coated film was tested foroxygen and carbon dioxide permeabilities and the results are given inTable 1.

EXAMPLE 1e

A one-mil thick film of polypropylene as in Example 1a was coated with atwo-package coating composition including: (1) an ungelledamine-functional polymeric adduct of Example J except the solvent was2-butoxyethanol and (2) EPON 828 epoxy. The ungelled amine-functionalpolymeric adduct (50 g total of a 31.6 percent by weight resin solution)was stirred as 3.67 g of EPON 828 epoxy was added, followed by additionof 0.097 g SF-1023 silicone. The equivalent ratio of epoxy groups toamine hydrogen equivalents in this mixture was about 0.21:1. The mixturewas applied and heated as in Example la to give a resultant clearbarrier film having high gloss, good flexibility and a dried filmthickness of barrier material of about 0.6 to 0.7 mils. The coated filmwas tested for oxygen and carbon dioxide permeabilities and the resultsare given in Table 1.

COMPARATIVE EXAMPLE 2

A polypropylene film as in Example 1 was coated with a mixture of acommercially available epoxy-amine adduct and EPON 828 epoxy. Thesereactants were mixed as follows so as to yield a 1:1 equivalent ratio ofepoxy groups to amine hydrogen equivalents. The epoxy-amine adduct (50 gtotal of a 42 percent by weight resin solids solution available as C-112epoxy curing agent from Shell Chemical Company) was mixed with 47 g ofthe EPON 828 epoxy. The coated film, drawn down and heated as in Example1, gave a flexible, clear coating. The testing results on this coatedfilm and those of an uncoated samples of the polypropylene are given inTable 1.

                  TABLE 1                                                         ______________________________________                                                      O.sub.2 Permeability                                                                    CO.sub.2 Permeability                                          % Amine N  (cc-mil/100 in.sup.2 -day-atmosphere                      Example  in Coating at 23° C. and 0% R.H.)                             ______________________________________                                        1a       4.65       3.1         13.9                                          1b       6.7        2.9-3.4     9.6-10.7                                      1c       9.0        2.1         2.8-3.1                                       1d       10.9       0.5         0.0                                           1e       9.0        0.1         0.2                                           Comp. 2  3.55       5.5         --                                            Polypropy-                                                                             --         155         --                                            lene                                                                          (uncoated)                                                                    ______________________________________                                    

EXAMPLE 3

Samples of the corona-treated polypropylene film as in Example 1 werecoated with a two-package coating composition including: (1) theungelled amine-functional polymeric adduct from Example D and (2) EPON828 epoxy. These reactants were mixed as follows: the ungelledamine-functional polymeric adduct (50 grams total of an 18.68 percent byweight resin solution in 2-butoxyethanol) was mixed with 23.8 g of theEPON 828 epoxy to form a coating composition, and heated as in Example 1with the exception that heating was for 30 minutes. One coated filmsample was clamped between two pieces of expanded aluminum metal andplaced in boiling water for about one hour to study the effect ofretort. Adhesion between the barrier material and the polypropylene wasunaffected. Results of the testing on samples before and after retortare given in Table 2.

EXAMPLE 4

Samples of polypropylene film were coated as in Example 1 with atwo-package coating composition including: (1) the ungelledamine-functional polymeric adduct of Example F and (2) a diglycidylether of butanediol having an epoxy equivalent weight of 102 (availableas ARALDITE RD-2 from Ciba-Geigy Corporation). These reactants weremixed as follows: the ungelled amine-functional polymeric adduct (50 gtotal of a 15.31 percent by weight resin solution in 2-butoxyethanol)was mixed with 6.1 g of the RD-2 epoxy to form a coating composition,which was drawn down and heated as in Example 3. One coated film samplewas subjected to boiling water as in Example 3 and results of testing onthe samples are given in Table 2.

EXAMPLE 5

A polypropylene film was coated as in Example 3 with a two-packagecoating composition including: the ungelled amine-functional polymericadduct of Example B and RD-2 epoxy. These reactants were mixed asfollows: the ungelled amine-functional polymeric adduct (50 g total of a15.1 percent by weight resin solution in 2-butoxyethanol) was mixed with7.14 g of the RD-2 epoxy to form a coating composition which was drawndown and heated as in Example 3. Results of testing on the coated filmare in Table 2.

EXAMPLE 6

A polypropylene film was coated as in Example 3 with a two-packagecoating composition including: (1) the ungelled amine-functionalpolymeric adduct of Example B and (2) a blend of aromatic and aliphaticepoxies. These reactants were mixed as follows: the ungelledamine-functional polymeric adduct (50 grams total of a 15.1 percent byweight resin solution in 2-butoxyethanol) was mixed with 0.38 epoxyequivalents of RD-2 epoxy and 0.62 epoxy equivalents of EPON 828 epoxyper one amine hydrogen equivalent (a total of 2.88 g RD-2 epoxy and 8.77g of EPON 828 epoxy) to form a coating composition which was drawndownand heated as in Example 3. Results of testing are given in Table 2.

EXAMPLE 7

A polypropylene film was coated as in Example 3 with a two-packagecoating composition including: (1) the ungelled amine-functionalpolymeric adduct of Example B and (2) a 1 to 1 by epoxy equivalentsblend of an aromatic and an aliphatic epoxy. These reactants were mixedas follows: the ungelled amine-functional polymeric adduct (50 g totalof an 18.68 percent by weight resin solution in 2-butoxyethanol) wasmixed with 6.45 g of RD-2 epoxy and 11.38 g of EPON 828 epoxy to form acoating composition as in Example 3 which was drawn down and heated asin Example 3. Results of testing on the coated film are given in Table2.

                  TABLE 2                                                         ______________________________________                                                   Coating  O.sub.2 Permeability                                      % Amine    Film     (cc-mil/100 in.sup.2 -day-atm                             Nitrogen   Thick-   at 23° C. and 0% R.H.)                                                                 Adhesion                                  Ex-   in       ness               after Loss                                  ample Coating  (mils)   before retort                                                                           retort                                                                              (percent)                             ______________________________________                                        3     4.97     0.3-0.35 2.8       2.7   0                                     4     6.00     0.1-0.15 1.8       1.7   0                                     5     6.20     0.1      1.2       --    0                                     6     4.78     0.25     2.6       --    0                                     7     5.94     0.65     2.8       --    0                                     ______________________________________                                    

EXAMPLE 8

Corona-treated polypropylene film samples were coated with a compositionconsisting of 18.7 g of an ungelled amine-functional polymeric adduct(prepared from a ratio of TETA to RD-2 epoxy of 7:6 in 81.3 g of2-butoxyethanol), and a blend of polyepoxides (12.9 g of RD-2 epoxy and23.8 g of EPON 828 epoxy), and optionally titanium dioxide pigment togive clear or colored barrier coatings. Application of the coatingcomposition was by drawing down onto the polypropylene film. The coatedfilms were then baked for 20 minutes at 160° F. Results of testing thesesamples is shown in Table 3 and demonstrate the reduction of oxygenpermeability by addition of pigment.

                  TABLE 3                                                         ______________________________________                                                       Parts by Weight (grams)                                                          1A    1B                                                    ______________________________________                                        Coating Ingredients                                                           Ungelled amine-functional                                                                         18.7    18.7                                              polymeric resin                                                               2-butoxyethanol     81.3    81.3                                              Polyepoxide blend   36.7    36.7                                              Titanium dioxide    --       55.33                                            Properties                                                                    Coating film thickness                                                                            0.8-1.2 0.8-1.0                                           O.sub.2 permeability                                                                               3.4     1.9                                              (cc-mil/100 in.sup.2 -day-atm)                                                Adhesion (% loss)   0        1                                                Adhesion after retort                                                                             0       10                                                (% loss)                                                                      ______________________________________                                    

EXAMPLE 9

A coating was applied to a high-density polyethylene bottle that hadbeen surface-treated on the interior surfaces by a fluoridation processas described in U.S. Pat. No. 862,284 with the exception that a smallamount of oxygen was added to the fluorine-containing nitrogen stream toprovide a fluoridation/oxidation of the bottle surface. The interiorbottle surface had a surface tension of about 50 dynes/centimeter. Thecoating included an ungelled amine-functional polymeric adduct similarto Example C (the resin having a theoretical molecular weight per aminehydrogen of 73.9), a tetrafunctional sorbitol-based polyepoxide havingan epoxy equivalent weight of 172 (available as ARALDITE XU GY 358aliphatic polyepoxide from Ciba-Geigy Corporation), and a small amountof a red dye to check uniformity of the resultant coating. The ungelledpolymeric adduct (20.2 g of a 29.7 percent by weight solution in1-methoxy-2-propanol) was stirred with a high-intensity mixer as 14.0 gof the polyepoxide was added. The interior of the bottle was coated bydipping in the coating composition, allowing excess coating compositionto drain off and heating at 200 ° F. for 15 minutes.

One bottle with a 0.4 mil thick coating, one bottle with a 1.0 mil thickcoating and an uncoated bottle were each filled with a methylenechloride-containing composition (Paint Stripper No. 99 from Red Devil).After 50 days at ambient temperature, the uncoated bottle had a weightloss of about 1.7 to 1.8 percent, the 1.0 mil coated bottle had a weightloss of about 1.5 percent and the 0.4 mil coated bottle had a weightloss of about 0.8 percent. Adhesion of the coatings to the bottles wasgood both before and after contact with the methylene chloride.

Example 10 describes the preparation of a coating in accordance with anembodiment of the present invention in which polyamine and polyepoxideare blended to form a barrier coating without the step of forming aprereacted adduct.

Examples 10, 11, and 12 involve the non-adduct embodiments of thepresent invention.

EXAMPLE 10

The following ingredients were mixed together at room temperature,provided with an ingestion period of 15 to 30 minutes.

25.0 grams 1-methoxy-2-propanol (available as Dowanol PM from DowChemical Co.)

58.2 grams EPON 828

27.0 grams tetraethylene pentamine

0.01 grams polydimethylsiloxane 0.01 (SF-1023 flow control agent fromGeneral Electric)

The mixture was sprayed onto a one mil thick corona treatedpolypropylene film (Phillips-Joanna PJX-2135) and baked at 200° F. for20 minutes. The cured film was hard, fairly glossy, 2.8 mils thick, hadan amine nitrogen content of 11.7 percent, and a calculated hydroxylcontent of 6.18 percent (assuming that the epoxy had fully reacted).After aging a few days, oxygen permeability of the coated film asmeasured by an Oxtran 1000 from Mocon, Inc., was 0.53 cc-mil/100 in²-day-atmosphere at 5° C.

EXAMPLE 11

The following ingredients were mixed together at room temperature,ingested for 15 to 30 minutes before being sprayed onto corona treated,1 mil thick Phillips-Joanna PJX-2135 polypropylene film:

30.0 grams Dowanol PM

58.2 grams EPON 828

20.0 grams TETRAD X (N,N,N',N' tetrakis(oxiranylmethyl) 1,3 benzenedimethanamine)

27.0 grams TEPA (tetraethylene pentamine)

5.26 grams CAB 551-0.01 solution (20% solids in methyl ethyl ketone)

0.02 grams SF-1023 polydimethylsiloxane flow control agent from GeneralElectric.

After spraying onto the substrate, the film was baked for 20 minutes as200° F. and aged for 2 to 3 days at room temperature. The cured film wasglossy and hard, had a thickness of 2.8 mils, had a calculated aminenitrogen content of 10.3 percent by weight and a hydroxyl content of6.07 percent by weight. The cured film was tested in an OXTRAN 1000permeability analyzer from Mocon, Inc., and the results were 1.3cc-mil/100 in² -day-atmosphere for oxygen and 0.39 cc-mil/100 in²-day-atmosphere for carbon dioxide.

EXAMPLE 12

The following ingredients were mixed together at room temperature,ingested for 15 minutes before being sprayed onto corona treated, 1 milthick Phillips-Joanna PJX-2135 polypropylene film:

18.0 grams Dowanol PM

36.0 grams TETRAD X (N,N,N',N' tetrakis(oxiranylmethyl) 1,3 benzenedimethanamine)

13.9 grams TEPA (tetraethylene pentamine)

0.02 grams SF-1023 polydimethylsiloxane flow control agent from GeneralElectric.

After spraying onto the substrate, the film was baked for 20 minutes as200° F. and aged for several days at room temperature. The cured filmwas glossy and hard, had a thickness of 1.5 mils, had a calculated aminenitrogen content of 14 percent by weight and a hydroxyl content of 12.3percent by weight. The cured film was tested in an OXTRAN 1000permeability analyzer from Mocon, Inc., and the results were 0.07cc-mil/100 in² -day-atmosphere for oxygen and 0.03 cc-mil/100 in²-day-atmosphere for carbon dioxide.

The following example involves the reaction of a polyepoxide-polyamineadduct with an amine-containing, tetra-functional polyepoxide.

EXAMPLE 13

50 grams of tetra glycidyl bis(p-amino phenyl)methane (MY-720 fromCiba-Geigy Corp.) were mixed with 15.64 grams butyl Cellosolve(2-butoxyethanol) at room temperature to yield a 70 percent solidsmixture. 6.23 grams of the mixture was blended with 50 grams of anadduct which is the reaction product of 7 moles TEPA (tetraethylenepentamine) and 6 moles of EPON 828, the adduct being 33.2 percent solidsin Dowanol PM (1-methoxy-2-propanol) solvent. 13.77 grams of butylCellosolve was then added. After 10 minutes at room temperature, themixture was sprayed onto flame treated polypropylene cups from KingPlastics Corp. at about 0.9 mil average dry film thickness and given a200° F. bake for 20 minutes. One cup was soaked in water at 120° F. forthree hours without exhibiting blistering or blushing. Another of thecoated cups was measured for oxygen permeation on a Mocon OXTRAN deviceat 71.6° F. and zero relative humidity and a rate of 0.1245 cubiccentimeters of oxygen per cup per 24 hours was recorded. This comparedto oxygen permeation of an uncoated cup of 2.947 cubic centimetersoxygen per cup per 24 hours. The calculated amine content of the barriercoating of this example was about 12.0 percent, and the calculatedhydroxyl content was about 7.36 percent (assuming complete reaction).

The following example illustrates increasing the hydroxyl content of abarrier coating by reacting a portion of the amine functionality in thepolyamine with glycidol prior to curing with a polyepoxide.

EXAMPLE 14

An adduct was made by reacting 7 moles of EPON 828 polyepoxide with 6moles of tetraethylene pentamine in 1-methoxy-2-propanol (Dowanol PM)solvent. 30 percent of the remaining amine hydrogens of the adduct werereacted with glycidol. The resulting modified adduct was 30 percent byweight resin solids. 71.86 grams of the adduct was mixed at roomtemperature with 2.87 grams N,N, N',N'-tetrakis(oxiranylmethyl)-1,3-benzene dimethanamine (TETRAD X), 25.26grams 2-butoxyethanol (butyl Cellosolve), and 0.01 gram SF-1023polydimethylsiloxane flow control agent from General Electric. Thecomposition was sprayed onto 1 mil thick polypropylene film(Phillips-Joanna PJX-2135) and baked at 200° F. for 20 minutes. Theresulting film was glossy and hard and had a calculated amine nitrogencontent of 10.5 weight percent and a calculated hydroxyl content of 13.5weight percent assuming complete reaction. The oxygen permeability forthe cured film as measured by an OXTRAN 1000 from Mocon Inc. was about0.15 cc-mil/100 in² -day-atmosphere at 30° C., dry conditions, and 0.10cc-mil/100 in² -day-atmosphere at 15° C., dry conditions. Carbon dioxidepermeability was tested on a PERMATRAN C-IV permeation test device fromMocon, Inc., for a film that had been baked at 140° F. for 20 minutesand was measured to be 0.33 cc-mil/100 in² -day-atmosphere at 25° C.

The following example demonstrates the inclusion of an alkanolamine toincrease the amine and hydroxyl group content of the barrier coating.

EXAMPLE 15

An adduct was made by reacting 7 moles of tetraethylene pentamine with 6moles of EPON 828 polyepoxide in 1-methoxy-2-propanol (Dowanol PM). AT33.5 percent total solids, 230.92 grams of this adduct was mixed with21.0 grams of diethanol amine. To this mixture was added 36.10 grams ofTETRAD X , 108.75 grams of additional Dowanol PM, and 111.18 grams of2-butoxyethanol (butyl Cellosolve). This composition was 25.0 percenttotal solids, had a theoretical amine nitrogen content of 11 weightpercent of the solid reaction product, and had a theoretical hydroxylcontent of 12.9 weight percent. The solvent ratio was 65/35 on a weightbasis Dowanol PM/butyl Cellosolve. The composition was applied to 1 milpolypropylene film and baked 15 minutes at 140° F. The film was glossyand hard, and when tested after several days aging at room temperatureexhibited oxygen permeability of 0.6 cc-mil/100 in² -day-atmosphere at30° C., dry conditions, and exhibited carbon dioxide permeability of 0.2cc-mil/100 in² -day-atmosphere at 30° C., dry conditions.

The following example demonstrates the improvement in barrier propertiesyielded by the inclusion of a small amount of water during theepoxy-amine reaction.

EXAMPLE 16

This example is the same as Example 15, except that at the point whenthe TETRAD X was added to the mixture, 6.72 grams of deionized water wasalso added. The resulting oxygen permeability of the film was 0.31cc-mil/100 in ² -day-atmosphere at 30° C., dry conditions, and thecarbon dioxide permeability was 0.03 cc-mil/100 in² -day-atmosphere at30° C., dry conditions.

The following example shows an embodiment in which an alkanolamine wasused in a preliminary step to partially defunctionalize a highfunctionality polyepoxide, thereby adding both amine and hydroxyl groupsto the polymer.

EXAMPLE 17

An amine functional adduct was prepared by first reacting 2 moles ofdiethanolamine with 1 mole of a tetra-functional epoxy (TETRAD X) toyield a diepoxy intermediate. One mole of this intermediate was reactedwith 7 moles of tetraethylene pentamine in Dowanol PM, and the resultingadduct was characterized by 20.6 percent total solids content, 16.6weight percent theoretical amine nitrogen content, 16.4 weight percenttheoretical hydroxyl content, and an active amine hydrogen equivalentweight of 134.5. A mixture was made of 67.1 grams of this adduct with9.5 grams of Dowanol PM, 30.92 grams of butyl Cellosolve, and 0.06 gramsof SF-1023 polysiloxane. The mixture was sprayed onto a 1 mil thick filmof polypropylene and baked for 10 minutes at 200° F., whereupon the filmexhibited oxygen permeability of 0.5 cc-mil/100 in² -day-atmosphere at30° C., dry conditions. This film has a theoretical amine nitrogencontent of 13 weight percent and a theoretical hydroxyl content of 16.5weight percent.

Although the present invention has been described with reference tospecific details for the sake of enabling those of skill in the art topractice particular embodiments thereof, it is not intended that suchdetails should be regarded as limitations upon the scope of theinvention, except to the extent they are included in the accompanyingclaims.

We claim:
 1. A polymeric gas barrier material comprising a curedamine-functional polymeric resin which is a reaction product ofpolyamine and polyepoxide, the polymeric gas barrier materialcharacterized as containing at least about 17 percent by weight total ofamine nitrogen and hydroxyl groups based on total weight of polymericpolyamine-polyepoxide reaction product.
 2. The gas barrier material ofclaim 1 wherein the polyamine is a prereacted adduct which is a reactionproduct of a polyepoxide and a polyamine.
 3. The gas barrier material ofclaim 1 wherein the polymeric barrier material has an amine nitrogencontent of at least 6 percent by weight based of total weight ofpolymeric gas barrier material.
 4. The gas barrier material of claim 1wherein the polymeric barrier material has a hydroxyl content of atleast 10 percent by weight based on total weight of polymeric gasbarrier material.
 5. The gas barrier material of claim 1 wherein theamine nitrogen plus hydroxyl content of the polymeric barrier materialis at least 20 percent by weight based on total weight of polymeric gasbarrier material.
 6. The gas barrier material of claim 1 comprising aliquid coating composition having a resin solids content of at least 50percent by weight.
 7. The gas barrier material coating composition ofclaim 1 comprising solvent having a flash point less than 140° F.
 8. Thegas barrier material of claim 1 wherein the polyepoxide includespolyepoxide having more than two epoxy groups per molecule.
 9. The gasbarrier material of claim 8 wherein the polyepoxide includes four epoxygroups per molecule.
 10. The composition of claim 1 wherein thepolyepoxide includes polyepoxide having amine groups.
 11. Thecomposition of claim 1 wherein the ratio of active amine hydrogens inthe polyamine to epoxy groups in the polyepoxide is from about 1:0.1 toabout 1:1.